Wire end ferrule

ABSTRACT

A wire end-sleeve consisting of a front cylindrical metal sleeve (2) and a rear injection-moulded plastic collar (4). In order to be able to insert two conductors (10,11) into a wire end-sleeve (1), the inside cross-section of the plastic collar (4) is oval and designed to be capable of taking two conductors (10,11) side by side.

DESCRIPTION

The invention relates to a wire end ferrule according to the preamble ofclaim 1.

PRIOR ART

Wire end ferrules of the generic type are disclosed in DE 2,941,770 C2or DE 3,314,295 C1. Such wire end ferrules are used to producesolderless electrical connections, a crimping tool being used to pressor crimp the stripped end of a conductor to the wire end ferrule. Such acrimping tool is shown, for example, in DE 2,614,577 B1.

Wire and ferrules consist of a front cylindrical metal tube or a metalsleeve having, integrally extruded or plugged thereon, a rear plasticcollar as insulating sleeve. The stripped part of the finely strandedconductor is inserted into the wire end ferrule from behind into theplastic collar, and crimped in the region of the metal sleeve, resultingin the permanent connection. The rear integrally extruded plastic collaraccommodates the conductor with the insulation as insulating sleeve.

The different diameters or dimensions of wire end ferrules are laid downin DIN 46 228 Part 4. In this case, the cylindrical plastic collar andthe front cylindrical metal tube are dimensioned such that in each caseonly one conductor can be properly inserted and crimped.

When conductors are mounted on switchboxes, as indicated, for example,in FR 1,468,859, FIG. 1, it frequently happens that a plurality ofconductors have to be simultaneously screwed onto a switch terminal. Forthis purpose, it is known for two conductors to be inserted into a wireend ferrule which fits in some shape or other, in order to be mountedjointly on a supply terminal. In this case, the cross-section of themetal tube is selected such that this corresponds approximately to twicethe conductor cross-section of the litz wires, so that the latter can beinserted. If such a cylindrical cross-section of the metal tube isselected, the associated cylindrical plastic collar of this wire endferrule is dimensioned in such a way that it cannot accommodate twojuxtaposed conductors. It therefore has to be brought by means ofmechanical deformation into an oval shape whose dimensional variationsare not, however, adapted to juxtaposed conductors. Moreover, it ispossible only with difficulty for such a deformation process of theplastic collar to be automated.

If a plastic collar is selected which has an inside diametercorresponding to two juxtaposed conductors, the cross-section of theassociated metal tube generally has excessive dimensions.

In known wire end ferrules, it is therefore disadvantageous that in thecase of small switching devices or terminals it is impossible, orpossible only with difficulty, to underclamp two conventional wire endferrules in order to continue the electrical connection.

ADVANTAGES OF THE INVENTION

The wire end ferrule according to the invention having thecharacterizing features of claim 1 has, by contrast, the advantage thatsaid ferrule is configured in such a way that it can accommodate twoconductors without any problem, without having to undertake a mechanicaldeformation of the plastic collar. Here, the invention proceeds from thefinding that adapting the cross-sectional ratios of the metal tube andthe metal sleeve must be performed in such a way that the latter in eachcase comprises a circular cylindrical cross-section which canaccommodate two conductor ends twisted one in another, while the ovalcross-section of the adjoining plastic collar is dimensioned such thatsaid collar can accommodate the two conductors in a juxtaposed fashion.A geometrical reshaping of the wire end ferrules is necessary to thisextent, that is to say the circular cylindrical cross-section of themetal tube largely corresponds to twice the cross-section of thestripped conductor, while the plastic collar of oval cross-section hasto accommodate two juxtaposed conductors with their insulating wrappers.

Further details of the invention are represented in the drawing andexplained in more detail in the following exemplary embodiment.

FIG. 1 shows a plan view of the wire end ferrule, half cut away,

FIG. 2 shows a plan view of the cross-section of the plastic collar,

FIG. 3 shows a side view of the wire end ferrule according to FIG. 1.

DESCRIPTION OF THE INVENTION

The wire end ferrule 1 represented in various views in FIGS. 1 to 3consists of a front cylindrical metal tube or a metal sleeve 2 having afront outside diameter d₁ and an inside diameter d₂. The cylindricalpart of the metal sleeve 2 extends over a length 1₁ and then opens outinto a conical section 3 having a taper angle of α₁ ≈40°. The overalllength of the metal sleeve 2 is specified by 12. The outside diameter ofthe conical section 3 is denoted by d₃.

The conical section 3 of the metal sleeve 2 is injection molded with aplastic collar 4 which has a front conical section 5 and a rearcylindrical section 6 of length 1₃. The overall length of the plasticcollar 4 is specified by 1₄. The plastic collar 4 starts from a lengthof 1₅ on the metal sleeve 2. The overall length of the wire end ferruleis specified by 1₆.

The taper angle of the plastic collar 4 in FIG. 1 is α₂ ≈45°. The innercircumferential surface 7 of the cylindrical part 6 of the plasticcollar 4 of length 1₃ likewise extends slightly conically with a taperangle of α₃ ≈3°. The above values hold for the plan view of the wire endferrule in accordance with FIG. 1.

In the side view of the wire end ferrule in accordance with FIG. 3, theplastic collar 4 has a front taper angle of α₄ ≈20° and a taper angle ofα₅ ≈5° for the inner circumferential surface. In this case, the conicalsection 3 of the metal sleeve 2 has the same taper angle of α₅ as theinner circumferential surface 7 of the plastic collar 4.

As may be seen in conjunction with FIGS. 1 to 3, the plastic collar 4 isprovided with an oval shape, as is particularly to be discerned in planview from FIG. 2. The wider end of the plastic collar 4 has an outerwidth of b₁ and an inner width b₂. This end is labelled with thereference 8. The narrower end 9 of the plastic collar 4, which has theshape of a circular segment, has an outer width b₃ and an inner widthb₄. The difference between these widths yields the wall thickness of theplastic collar 4. The conical shape of the inner circumferential surface7 of the plastic collar 4 leads after the length 1₃ to an inner width b₅as the wider and be as the narrower inside length.

As may be seen, furthermore, from FIGS. 1 to 3, the wire end ferrule 1according to the invention serves to accommodate two conductors 10, 11which in each case have an inner conductor litz wire 12 and, surroundingthe latter, an insulating wrapper 13. The conductors 10, 11 have anoutside diameter d₄ and the conductor litz wires 12 an outside diameterd₅.

The wire end ferrule 1 is dimensioned with respect to its metal sleeve 2in such a way that the cross-sections of the conductor litz wires 12 ofthe two conductors 10, 11 can easily be inserted into the metal tube 2after they have been stripped. The inside cross-section of the metalsleeve 2 must therefore amount to at least the sum of the twocross-sections of the conductors 10, 11.

In like manner, the inner width b₂ at the end of the plastic collar 4 orin the front region 14 of the circumferential surface 7 of the cone,that is to say after approximately the length 1₃, must be dimensioned insuch a way that the two conductors 10, 11 can be juxtaposed with theiroutside diameter d₄. The widths b₂ and b₅, respectively, must thereforeamount to approximately twice d₄ (see FIGS. 1 and 2). The same holds forthe inner width b₆ in the front region 15 of the circumferential surface7 of the cone in FIG. 3, which likewise has to correspond approximatelyto the outside diameter d₄ of the conductors 10, 11. In the exemplaryembodiment represented, the insulating wrapper 13 is not pushed as faras the foremost region 14, 15 of the conical inner circumferentialsurface (1₃), but is pushed in only up to a length 1₇. An adequatepush-in length of the insulating wrapper 13 is decisive.

By tuning the cross-sections of the plastic collar 4 as a function ofthe juxtaposed conductors 10, 11 which are to be inserted, and by tuningthe cross-section of the associated metal sleeve 2 for adaptation to thecross-sections of the two conductor litz wires 12, which are to beinserted, of the two conductors 10, 11, the wire end ferrule is adaptedto the geometrical conditions of the conductors to be manipulated.

The invention is not restricted to the exemplary embodiment describedand represented. Rather, it also comprises all developments by theperson skilled in the art within the scope of the concept according tothe invention. Instead of an oval cross-section of the plastic collar,it is also possible to use a rectangular cross-section with a lateralboundary shaped like a circular segment or the like.

It is claimed:
 1. Wire end ferrule for accommodating finely strandedconductors which form a crimp connection with the wire end ferrule,having a front cylindrical metal sleeve for accommodating a strippedconductor part and having, connected thereto, a rear plastic collar asinsulating sleeve for accommodating the conductor with an insulatingwrapper, characterized in that for the purpose of simultaneouslyaccommodating two conductors (10, 11) in a wire end ferrule (1) thecircular inner cross-section (diameter d₂) of the metal sleeve (2) isdimensioned in such a way that it accommodates the two strippedconductor litz wires (12) of the conductors (10, 11), and in that theplastic collar (4) adjoining the metal sleeve (2) has an approximatelyoval or rectangular inner cross-section (4), whose longer width b₂ isdimensioned in such a way that at least two juxtaposed conductors (10,11) can be inserted together with their insulating wrapper (13).
 2. Wireend ferrule according to claim 1, characterized in that the plasticcollar (4) has a free, approximately oval inner cross-section whoselonger width b₂ corresponds approximately to the width of two juxtaposedconductors (10, 11) including the insulating wrapper (13) and whoseshorter width b₄ corresponds approximately to the diameter d₄ of theconductors (10, 11), and in that the circular cylindrical cross-sectionof the metal sleeve (2) has a free inner cross-section which correspondsapproximately to the sum of the cross sections of the two conductor litzwires (12) of the conductors (10, 11).